Ore concentration.



L. A. WOOD.

ORE CONCENTRATION;

APPLICATION FILED JUNE 2, 1914.

1,155,861. Patented 0015.5,1915.

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LOUIS ALBERT WOOD, OF LONDON, ENGLAND, ASSIGNOR TO MINERALS SEPARATION AMERICAN SYNDICATE (1913) LIMITED, LONDON, ENGLAND.

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Specification of'Lettei'a Patent.

Patented Oct. a, 1915.

To all whom it may concern: I

Be it known that I, Lorns ALBERT Woon,

a subject of the King of England, residing at London, in England, have invented certain new and useful Improvements in Ore Concentration, of which the following is a specification.

monly Worked and as described for example in the United States Patent No. 835120 granted November 6th, 1906, the finely powdered ore is suspended in acidified water containing a small proportion of an oily substance and the pulp is ag1tated so as to beat into it the supernatant air whereby a froth is formed containing the metalliferous matter. There have been. many modifications of the agitation froth process such as the replacement of the oil by other frothing agents, in some cases soluble in water. It has also been proposed to dispense with the use of acid in certain cases or to employ other chemical agents.

Again, in processesof the Potter type as described for example in United States Patent N 0. 7761.45, granted November 29th, 1904, the finely powdered ore is mixed with water containing sulfuric acid and heat is applied in such a way as to bring about the chemical evolution of gaseous bubbles in the pulp, the evolved bubbles attaching themselves preferentially to certain metalliferous particles and rising and floating on the surface. 1

Various types of apparatus have been devised for carrying these processes into efiect, for example United States Patent No. 763749 granted June 28th, 1904, describes a method and apparatus for carrying out the Potter process in which the minerals in the finely divided condition are subjected to the action of an acidulated solution which results in the formation of gas bubbles to which certain particles of the minerals adhere, the said mineral loaded bubbles being directed upwardly to the surface of the solution where they burst and release said par- .ticles which are thereupon precipitated andcollected in suitable troughs.

In United States Patent No. 1093463 granted April 14th, 1914, are described amethod and apparatus for concentrating ores by gaseous flotation of certain mineral partlcles in liquid in which the agitation froth as it is formed is caused to fall over a trap or wall below the level of the free-air surface whereby the froth is collected and removed from the pulp before the bubbles can burst.

Hitherto it has been known that without the use of any oil or other frothing agent, and without necessarily using acid or heat, sulfid particles in an aqueous pulp would preferentially attach to themselves bubbles or films of air which have been suitably introduced into the pulp and that such sulfid particles could be raised to the surface by bubbles or films 'or air. Such bubbles with the associated mineral do not readily form a persistent and coherent froth and the phenomenon has not therefore received any practical embodiment. q

' According to this invention a pulp-consisting of powdered ore freelysuspended in Water is subjected to the admission of gas or a mixture of gases such as air which is disseminated in such a way that the gaseous films or bubbles preferentially attach themselves to themetalliferous particles such as sulfids and rise toward the surface of the liquid. The ore pulp to which the air is admitted mayaccording to this invention be subjected to agitation. When the bubbles at or near the surface of the liquid discharge the mineral the latter'is caught in a trough below the level of the liquid.

The accompanying drawings illustrate diagrammatically a suitable ap aratus for carrying this invention into e ect, which consists of an upright vessel A preferably rectangular having an inlet for air B at the bottom, with a valve B in the inlet conduit. The vessel A is provided at the bottom with an agitating device such as a propeller C.

duced under pressure or otherwise into the pulp which is then agitated so as to bring the finely divided air into contact with the suspended ore particles whereupon the gaseous bubbles with the associated particles rise means may be provided for removing the selected particles intermittently or continuously, for example the vessel may be provided at the bottom of the trough with an outlet G leading to a concentrate launder G The ore pulp may be fed to the vessel through the inlet H and the tailing ore pulp which has been depleted of certain mineral contents may be removed through the outlet J. In the example of apparatus illustrated there is one plate E forming a trough to receive the concentrates, but two or more such plates may be used or the apparatus may be otherwise arranged in such a way that when the gaseous bubbles at or near the.surf ace of the liquid discharge the associated mineral, the latter is caught in a trough or receiver below the level of the liquid.

The following are examples of the practi cal application of this invention.

A powdered ore containing copper sulfid was mixed with water at ordinary temperature and without any addition of frothing agent or chemical agent. The pulp was subjected to agitation and aeration in an apparatus of the type described and it was found that the bubbles of air selected the particles of copper sulfid and raised them toward or tothe surface of the liquid where the bubbles discharged the associated mineral into the receiving trough from which they were removed, an efficient separatioirof thevalues from the gangue being thus obtained. Again, Broken Hill tailings crushed to 60 mesh were mixed with four times their weight of water at atmospheric temperature containing about 1% of sulfuric acid on the weight of ore. This pulp was subjected to agitation and aeration as above described and a good recovery of zinc and lead sulfids of a high grade was obtained. In some cases it was found advantageous to heat the pulp to a temperature of 50 to 60 C. The use of oil or any other frothing agent is avoided as such use under the conditions specified tends to result in the formation of a more or less persistent and coherent froth, whereas according to this invention the formation of such a froth is avoided. Examples have been given for the separation of sulfids from gangue but the method and apparatus are applicable also to the separation of different sulfids from one another as wellas from gangue. The conditions such as the amount of aeration have to be varied according to the nature of the ore and the degree of crushing and a simple preliminary test is necessary to determine the best conditions for the treatment of any particular ore.

; What I claim as my invention and desire to secure by Letters Patent is 1. A process of concentrating ores which consists in subjecting the powdered ore sus-' pended in water free from frothing agents to the admission of gas, forcefully disseminating the gas through the pulp in such a Way that the gaseous bubbles preferentially attach themselves to certain mineral particles and rise toward the surface and discharge their mineral load within the pulp, and catching and removing such discharged mineral below the surface of the liquid.

2. A process of concentrating ores, which consists in introducing gas to the lower zone of an ore pulp free from frothing agents, subjecting such ore pulp in its lower zone t6 agitation whereby the gas will be forcefully disseminated through the pulp, maintaining the upper zone of the pulp in a state of comparative quiescence, whereby gas bubbles attach themselves selectively to certain mineral particles and rise toward the surface and discharge their mineral load within the pulp, and catching and removing such discharged mineral below the surface of the liquid.

3. A process of concentrating ores which consists in subjecting a liquid mass of ore pulp free from frothing agents to continuous agitation in its lower zone, introducing fresh ore pulp continuously to said liquid mass, removing depleted ore pulp continuously from said liquid mass, introducing gas continuously to the lower zone of the pulp so that it will be forcefully disseminated through the pulp by the agitation of the pulp in the lower zone thereof, maintaining the upper zone of the pulp in a state of comparative quiescence, whereby gaseous bubbles attach themselves selectively to certicles and rise toward the surface and discharge their mineral load in the pulp, and catching and removing such discharged min eral below the surface of the liquid.

5. A process of concentrating sulfid ores which consists in subjecting the liquid mass of ore pulp free from frothing agents to agitation in its lower zone, introducing air to the lower zone of the pulp so that it will be forcefully disseminated through the pulp by the agitation of the lower zone thereof, ch-

tain mineral particles and rise toward the structing the turbulence of the pulp in its upper zone, whereby air bubbles attach themselves selectively to certain sulfid particles and rise toward the surface and discharge their,load of sulfid particles within the pulp, and catching and removing said discharged sulfid particles below the surface of the liquid. 1

6. A process of concentrating sulfid ores which consists in subjecting a liquid mass of ore pulp free from :frothing agents to continuous agitation in its lower zone, introducing fresh ore pulp continuously to said liquid mass, and removing depleted ore pulp continuously from said liquid mass, introducing air continuously to the lower zone of the pulp so that it will be forcefully disseminated through the pulp by the agitation tively to certain sulfid particles and rise toward the surface and discharge their load of sulfid particles within the pulp, and catching and removing such discharged 'sul-' fid particles below the surface of the liquid.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

LOUIS ALBERT WOOD.

' Witnesses: WILLIAM H. BALLANTYNE,

HARRY B. BLIDGE. 

